Liquid crystal display device and driving method thereof

Abstract

In a display device including a backlight and a display panel, the area of the backlight is divided into a plurality of unit regions; the display panel includes pixels which are larger in number than the unit regions; a frame rate of image data input to the device is converted to perform display while part of the unit regions in which black is displayed is in a non-light emission state; and the driving frequency of the backlight is converted in accordance with the display.

What is claimed is: 
     
       1. A liquid crystal display device comprising:
 a backlight; and 
 a display panel, 
 wherein the backlight is divided into a plurality of unit regions configured so that brightness of each of the plurality of unit regions is individually controlled, 
 wherein the display panel includes pixels which are larger in number than the plurality of unit regions, 
 wherein the backlight is configured to have a period during which the brightness of each of the plurality of unit regions is controlled in accordance with gray scale levels of images, and 
 wherein a maximum brightness of the plurality of unit regions when displaying one of the images is determined in accordance with an average value of gray scale levels of the one of the images so that the maximum brightness is increased when the average value is reduced and the maximum brightness is decreased when the average value is increased. 
 
     
     
       2. The liquid crystal display device according to  claim 1 ,
 wherein the backlight has three levels of brightness. 
 
     
     
       3. The liquid crystal display device according to  claim 1 , wherein the backlight comprises a plurality of light emitting diodes. 
     
     
       4. The liquid crystal display device according to  claim 1 ,
 wherein a first voltage, a second voltage and a third voltage are input to a pixel, in this order, each of the first voltage, the second voltage and the third voltage including an over drive voltage depending on a gray scale level, and 
 wherein the liquid crystal display device is configured to determine the second voltage in accordance with the first voltage and the third voltage. 
 
     
     
       5. The liquid crystal display device according to  claim 1 ,
 wherein a brightness of each unit region included in the backlight can be set in accordance with brightnesses relationships between unit regions of the backlight. 
 
     
     
       6. A liquid crystal display device comprising:
 a backlight; and 
 a display panel, 
 wherein the backlight is divided into a plurality of unit regions configured so that brightness of each of the plurality of unit regions is individually controlled, 
 wherein the display panel includes pixels which are larger in number than the plurality of unit regions, and 
 wherein a maximum brightness of the plurality of unit regions when displaying one of images is determined in accordance with an average value of gray scale levels of an entirety of one of the images so that the maximum brightness is increased when the average value is reduced and the maximum brightness is decreased when the average value is increased. 
 
     
     
       7. The liquid crystal display device according to  claim 6 ,
 wherein the backlight has three or more levels of brightness. 
 
     
     
       8. The liquid crystal display device according to  claim 6 , wherein the backlight comprises a plurality of light emitting diodes. 
     
     
       9. The liquid crystal display device according to  claim 6 ,
 wherein a first voltage, a second voltage and a third voltage are input to a pixel, in this order, each of the first voltage, the second voltage and the third voltage including an over drive voltage depending on a gray scale level, and 
 wherein the liquid crystal display device is configured to determine the second voltage in accordance with the first voltage and the third voltage. 
 
     
     
       10. The liquid crystal display device according to  claim 6 ,
 wherein a brightness of each unit region included in the backlight can be set in accordance with brightnesses relationships between unit regions of the backlight. 
 
     
     
       11. A liquid crystal display device comprising:
 a first backlight unit region, 
 a second backlight unit region; and 
 a display panel, 
 wherein the first backlight unit region and the second backlight unit region are configured so that brightness of the first backlight unit region and the second backlight unit region are individually controlled, and 
 wherein a maximum brightness of the first backlight unit region and the second backlight unit region when displaying one of images is determined in accordance with an average value of gray scale levels of an entirety of the one of the images so that the maximum brightness is increased when the average value is reduced and the maximum brightness is decreased when the average value is increased. 
 
     
     
       12. The liquid crystal display device according to  claim 11 ,
 wherein each of the first backlight unit region and the second backlight unit region has three or more levels of brightness. 
 
     
     
       13. The liquid crystal display device according to  claim 11 , wherein the first backlight unit region comprises a plurality of light emitting diodes. 
     
     
       14. The liquid crystal display device according to  claim 11 ,
 wherein a first voltage, a second voltage and a third voltage are input to a pixel, in this order, each of the first voltage, the second voltage and the third voltage including an over drive voltage dependent on a gray scale level, 
 wherein the liquid crystal display device is configured to determine the second voltage in accordance with the first voltage and the third voltage. 
 
     
     
       15. The liquid crystal display device according to  claim 14 ,
 wherein the brightness of the first backlight unit region is configured to be larger than the brightness of the second backlight unit region while the first voltage is input, 
 wherein the brightness of the first backlight unit region is configured to be the same as the brightness of the second backlight unit region while the second voltage is input, and 
 wherein the brightness of the first backlight unit region is configured to be smaller than the brightness of the second backlight unit region while the third voltage is input. 
 
     
     
       16. The liquid crystal display device according to  claim 11 ,
 wherein a brightness of each unit region included in the backlight can be set in accordance with brightnesses relationships between unit regions of the backlight.